Hearing aid



SePt- 4 1951 w, DUBILIER 2,566,761

HEARING AID Filed Dec. '7, 1948 l NV E N TOR.

'iii-5" W'wm.

TTORNEYLSY Patented Sept. 4, 1951 UNITED STATES PATENT OFFICE 3 Claims.

My present invention relates to hearing aids and more particularly to a compact simplified composite microphone structure for a hearing aid wherein a single microphone casing contains the current supply and all other elements of the hearing aid, except the ear phone connected thereto.

The primary object of my present invention is the utilization in connection with the microphone portion of the hearing aid of a novel type of spring wound variable resistor so arranged that when it is compressed or expanded longitudinally the coils of the spring separate or are brought together successively and not simultaneously; for each separation between adjacent turns of the spring wound resistor a full turn of the resistor is introduced in the circuit, and for each contact between two turns, a full turn of the spring is eliminated or shunted out of the circuit.

Another object of my invention is to utilize in connection with a microphone of the foregoing type a conically wound resistor spring so arranged that as volume peaks are reached beyond a desirable amplitude, successively smaller turns of the resistor spring are introduced into and shunted out of the circuit.

Another object of my invention is the provision and utilization of a circular or doughnut shaped battery in the microphone housing or casing as the source of current supply, the center opening in the said battery providing a recess in which the spring or the housing for the resistor spring may be received.

My invention contemplates mounting a microphone diaphragm so that its vibrations will compress and expand the spring, varying the resistance of the resistor spring.

The resistor spring, the battery, and the ear piece are connected in series so that variations in the resistance of the spring will result in variations in current i'low to the ear piece and thereby vary the intensity of the vibrating element in the ear piece which may be of a standard type in accordance with the amplitude variations in the current, which in turn result from the amplitude variations of the microphone diaphragm; and, of course, the frequency of the vibrations of the vibrating element in the ear piece will correspond to the frequency of the vibrations of the diaphragm in the microphone.

The foregoing and many other objects of my invention will become apparent in the following description and drawings in which:

Figure 1 is a vertical cross-sectional view through my novel composite microphone forming a hearing aid.

Figure 2 is an exploded view oi' the hearing aid of Figure 1.

Figure 3 is an elevation of a portion of the main housing of the unit of Figure 1 taken from line 3-3 looking in the direction of the arrows.

Figure 4 is an elevation of the battery to be utilized in connection with the unit of Figure 1;

Figure 5 is a schematic view showing the circuit diagram of the unit of Figure 1.

Figure 6 is an enlarged view of the spring resistor of Figure 1.

Referring now to the gures, the composite hearing aid housing I0 is an annular structure of insulating material having the bell-shaped front wall II which denes with the annular wall IIJ the annular chamber I2. The mouth of the bellshaped front wall II is provided with an annular ledge I3 against which the diaphragm I 4 may be seated.

The diaphragm I4 is then held in position by the ring clamping cover I5 having the internal ledge I6 which seats against the diaphragm and the threads II which engage the thread I8 on the front of the annular wall I 0.

The closed rear portion 20 of the bell-shaped wall II extends up to or beyond the rear portion of the annular wall I0 and is provided with the threaded insert 2| which receives the adjustment screw 22, the adjustment screw 22 being longitudinally movable therein by small increments as it is rotated.

The resistor spring 25 has one end 26 thereof soldered in the notch 2'I of the adjustment screw 22 and the other end 28 of the resistor spring is soldered to the wire 29 attached at the center of the diaphragm. Vibrations of the diaphragm will thus result in longitudinal vibrations of the resistor spring 25 to vary its resistance in accordance with the amplitude of the vibrations of the diaphragm I4 at a frequency which will correspond to the frequency of the vibrations of the diaphragm I4.

A sponge rubber or other soft snubbing element 20, 3U, preferably of a shape to correspond to the interior shape of the resistor spring 25 is inserted in the spring 25 to prevent extraneous vibrations of the spring 25 so that all vibrations thereof will be in response only to vibrations of the diaphragm I4.

A circular or doughnut shaped battery 32 having the circular recess 33 is provided, the said battery having the usual electrodes and electrolyte and being so shaped that it fits within the annular chamber I2 formed by the two walls I0 and II. The circular opening 33 in battery 32 iits over the bell-shaped wall II so that the rear portion 20 projects beyond the battery, thereby making the adjustment screw 22 accessible.

A cover 35 having a thread 3B and a circular opening 31 is mounted on the rear end of the annular Wall Ill with the thread 36 interengaging with the thread 4i) of the wall Hl to secure the battery in place. The circular opening 31 in the cover 35 provides clearance for the rear end 20 of the bell-shaped Wall ll so thatthe adjustment screw 22 lis always accessible even while the 'unit is closed.

To replace the battery, it is then necessary only to remove the cover 35, remove the battery, insert the new battery, and replace the cover 35.

If desired, appropriate spring jme'ans Amayl be mounted on the interior of cover 35 to hold the battery tightly in position. The 'annular wall vl0 less. and all other parts of the unit may be correspondingly small.

The circular battery which fills all of the space in the unit l0, except for the space occupied by the spring resistor 25, provides a single battery having an effective size much greater than any previously possible for use in such small spaces.

Thus, although the entire unit need not be more than one inch or 'one inch and' a: half in diameter, the provision "of a circular battery makes possible an outer electrode having the larea of a battery three or more inches long and of the unit may be provided on its interior with` the key i2 which ridesf-in the keyway i3 of the battery .32. so that the batteryvmay be .inserted at only the exactly correctl angular position :to make proper contact.

' The battery is provided with two contact elements 50, 5i in a manner well-'known in the art connected `vto the electrodes of the battery and, of course, insulated from each other. The end '28 of the spring is connected to the wire 55, preferably being soldered thereto or in any other suitable manner.

'The wire 55 is, of course, a highly flexible wire permitting free vibration of spring 25. W'ire 455 is .soldered to the metal insert 56 which passes through wall H of the housing. Wire `5'! is .soldered lto the opposite end of the metal insert '56 .and passes through the wall it to be connect ed to wire 58 leading to the ear piece 55.

.'-Ihe other end- 2510i the spring resistor -25 is soldered to the flexible wire tl, which in turn is connected to the metal insert'Z passing through the wall vI I. The-opposite end of the metal insert 62 has connected thereto the wire 63 which is connected to the stationary contact 6d, which preferably is a spring biased contact member.

Contact 5d engages the electrode contact 5l of the battery 32. Electrode '5B of the Ibattery 32 engages contact Y55 which is a contact similar to the 'contact 64 but is, of course, insulated therefrom. Contact is connected by wire '55 which passes through the wall l5 to wire 61 connected to the ear .piece t9.' i

Thus, as seen in Fig-ure 5, as well as in Figures 'l' and 2the circuit for energizing the ear piece Bil is'frcm 'terminal :5i of the battery 32 to stationary contact 6ft in the housing, then through 'wire E33, metal insert 52, wire 6l, through 'the spring resistor 2'5, then through wire 55, metal insert 55, wire 5i, wire 5% to the ear `piece 65, then through wires 61 and 66 back to contact 65 in engagement with'terminal 5t of the battery.

Vibrations of the diaphragm I4 will result in corresponding longitudinal vibrations of 'the spring resulting further in varying the resistance of the spring 25 in accordance V'with the amplitude of the vibrations of diaphragm I4, at a frequency corresponding to the frequency of the vibrations of diaphragm It.

The amplitude and frequency of the current passed through the `ear piece 50 will thus be a function .of the amplitude and frequency of vibrations of diaphragm -I 4. p

VSince resistorV springs of the type vof spring `25 may be made extremely small, the resistor spring l25 maybe as small as of an inch long and-.even

an inner electrode of corresponding length, together with the provision of space for such electrolyte to 'render the battery as efficient in operation as a straight battery of the order of three inches long.

Thus, the combination of the resistor spring and the circular battery make possible the creation ofa small compact hearing aid unit',i-the full dimensions .of which (aside from 'the ear .piece Aand its cord) .need be not more than '-l to `1.5 inches hin diameter and not more than .5 to yi inch in thickness.

'The vutilization of my novel circular batteily makes possible also the utilization of other 'ty-pes of variable resistance elements for use in conneetion with a diaphragm.

Thus, instead of the spring resistor 25, a bare resistance wire may be Wound 'over insulation arounda magnetic core. The 'turns of the wire Amay then be bridged by a high-ly conductive ferrous `strip normally biased smoothly againS-tthe wire by the magnetic core. One :end ofthe strip; however, isy lifted `awayfrom the turns ofthe wire and secured to the center of the diaphragm, Vibrations of -the'diaphragm` will cause the cofrductivef'strip to bridge more or 'fewer'turns of the resistance wire in accordance `with the amplitude of the vibrations of lthev diaphragm, thereby varying the resistance `of the resistance wire proportionally to the 'amplitude' of the 'vibrations of the diaphragm and at a frequency correspor'idff ing tothe frequency Vof the diaphragm.

The resistance wire may then be connected the circuit in the 'same vmanner as that described in connection `with Figures 1 to '5 'as a 'substitute `for the spring resistor 25. v f`vv In the foregoing' I have described my invention solely in connection v'with 'specific illustrative emeA bodimei'ts thereof. Since many variations and modifications of my invention will now .be .obvious to those skilled in the art, I prefer v-tofbe bound not by the speciiic disclosures hereinicovnf.- tained but only by the appended claims.

Iclaim:

1. A hearing aid ncomprising microphone, 9.1 housing therefor, `said microphone including a diaphragm, a variable electrical resistance meme ber, a mechanical connection between -said resistance member and said diaphragm for varying the electrical resistance of said member in re spense to vibrationv of said diaphragm; said nous ing having an annular chamber for supporting a battery -`surrounding said microphone, and an annular battery within said chamber. s

2v. A hearing aid comprising a microphone inf, cluding a diaphragm and -a variable electrical resistance member `comprising a resilientlconical wire helix., the turns thereof being successively movable into and out of engagementwth .each other to vary the electrical resistance then-inf, a mechanical connection between saidv resistance member and said diaphragm for varying the-elec;l

trical resistance ot said member in response to vibration of said diaphragm.

3. A hearing aid comprising a microphone including a diaphragm and a variable electrical resistance member comprising a resilient conical 5 electrical resistance of said member in response to vibration of said diaphragm.

WILLIAM DUBILIER.

REFERENCES CITED The following references are of record in the file of this patent:

Number 8 UNITED STATES PATENTS Name Date Cuttriss Dec. 15, 1891 Beck et a1 Mar. 27, 1900 Plecher July 31, 1900 Frazier Dec. 10, 1901 Neudoriler Sept. 30, 1913 Mitchell Mar. 17, 1914 Hastings Dec.. 19, 1916 Rooney May 29, 1923 Newth June 15, 1926 Newth Feb. 8, 1927 Courcy et a1. Aug. 14, 1945 Tresise et al. July 22, 1947 

